Conventionally, when finger assignment for RAKE reception is performed by a path search processing section in a DS-CDMA (Direct Sequence-Code Division Multiple Access) system, a nondirectional state delay profile is created using a nondirectional received signal.
The path search processing section in a conventional radio base station apparatus will be described using FIG. 1. FIG. 1 is a block diagram showing the configuration of a convention 1 radio base station apparatus.
Uplink signals received via antennas 1 are input respectively to RF circuits 2. In the RF circuits 2, the received signals are down-converted. The down-converted signals undergo A/D conversion by an A/D converter not shown in the drawing, and become baseband signals. These baseband signals undergo despreading processing by matched filters (MF) 3, and are then output to an adaptive array antenna (hereinafter abbreviated to “AAA”) reception circuit 4. In the AAA reception circuit 4, the despread signals are multiplied by a predetermined reception weight, and undergo AAA reception processing. A signal on which AAA reception processing has, been performed is sent to a demodulation circuit 5, undergoes demodulation processing, and becomes receive data.
In addition, the output of an RF circuit 2 is sent to a matched filter 6, and after despreading processing, is sent to a delay profile circuit 7. The delay profile circuit 7 creates a delay profile using the despread signal, and outputs the result to a path search processing section 8. The path search processing section performs finger assignment based on the delay profile, and detects the despreading timing for AAA reception processing. This despreading timing is output to the matched filter 3.
In the above-described method, transmission power control is performed on the premise that the SIR (Signal to Interference Ratio) is improved by AAA reception, and a nondirectional received signal (signal prior to AAA reception processing) is used for finger assignment. However, when a nondirectional received signal is used, the SIR deteriorates greatly and accurate finger assignment is not possible with a delay profile based thereon. There is consequently a problem of deterioration of demodulation capability, and as a result, high reception power is necessary to perform correct finger assignment, and adjustment is carried out by means of transmission power control. This means that, despite the use of a reception AAA, it is not possible to achieve SIR improvement effects due to its directional control.